Circuit breaker control system



Inventor: Arvid E. Anderson,

His Athornes.

A. E. ANDERSON CIRCUIT BREAKER CONTRQL SYSTEM Onginal Filed July 22 1931 Feb. 23, 1943.

Reissued Feb. 23, 1943 22,273 I CIRCUIT BREAKER CONTROL SYSTEM Arvid E. Anderson, Haverford Township, Delaware County, Pa., assignor to General Electric Company, a corporation of New York Original No. 1,893,348, dated January 3, 1933, Se-

rial No. 552,448, July 22, 1931. Application for reissue May 28, 1942, Serial No. 444,879

10 Claims.

My .invention relates to circuit breaker control systems and particularly to systems for controlling the operation of a circuit breaker which connects a supply circuit to a load circuit and the operation of circuit breakers which respectively connect load circuits to the load bus so that when a fault occurs on any load circuit, the circuit breakerin the supply circuit is opened first, then the circuit breaker in the faulty circuit is opened and then the circuit breaker in the supply circuit is rec-losed, and one object of my invention is to provide an improved arrangement for accomplishing this result.

My invention will be better understood from the following description when taken in connec tion with the accompanying drawing which dia-- grammatically illustrates a circuit breaker controlsystem embodyingmy invention and its scope will be pointed out in the appended claims.

Referring to the accompanying drawing, I represents a circuit breaker which is arranged-to connect a supply circuit 2 to a load bus 3. A plurality of load circuits 4 are respectively arranged to be connected to the load bus 3 by circuit breakers 5. The circuit breakers I and 5 may be of any suitable type, examples of which are well known in the'art. As shown in the drawing, the circuit breaker I .is of the latched-in type and is provided with a trip coil 6 which, when sufliciently energized, releases a latch 1 so that the circuit breaker opens, and with a closing coil 8 which, when energized, closes the circuit breaker. The circuit breakers 5 are also shown as latched-in circuit breakers and are respectively provided with trip coils I which, when sufficiently energized, release the latches II which hold the circuit breakers in their closed position. In the particular embodiment of my invention shown in the drawing, it is assumed that the circuit breakers are manually closed but it will be obvious that any suitable closing means, examples of which are well known in the art, may be provided for closing the circuit breakers. Also in order to simplify the disclosure, only the control apparatus for automatically opening one of the circuit breakers 5 is shown since the control apparatus of all of the circuit breakers 5 may be the same.

In order to effect the opening of the circuit breaker I in response to a vpredetermined abnormal condition, such as fault, on a load circuit 4,

energized in accordance with the amount o'fcurrent supplied to all of the load circuits 4 by the supply circuit. The trip coil 6 is arranged so that a predetermined fault on any load circuit causes the trip coil 6 to be sufiiciently energized to release the latch l and allow the circuit breaker ,I to open.

Each load circuit 4 has associated therewith suitable means for effecting the disconnection thereof from the bus 3 in response to predetermined abnormal conditions on the respective load circuit, as shown, each circuit 4 has associated therewith an overload relay I3, the operating coil of which is connected by means of a current transformer I4 to the associated load circuit 4 in such a manner that the operating coil of the overload relay is energized in accordance with the current in the load circuit. Each overload relay I3 is arranged so that it closes its contacts I5 when the current in the associated load circuit 4 exceeds a predetermined amount. Each overload relay I3 is also preferably arranged in any suitable manner, examples of which are well known in the art, so that after the contacts I5 of the relay are closed, they remain closed indebreaker 5 are closed. Each auxiliary relay I1 is designed in any suitable manner so that its contacts I8 are closed as soon as the relay is energized and remain closed for a predetermined time after the relay is deenergized. Each auxiliary relay I1 controls the circuit of the trip coil III of the associated circuit breaker 5 and the closing coil 8 of the circuit breaker I so that when the circuit breaker I opens while the contacts l8 of auxiliary relay I! are closed, the circuit breaker 5 associated with the closed contacts I8 is opened and then the circuit breaker I is reclosed. In this manner, the circuit breakers are selectively controlled so that when a predetermined fault occurs on any load circuit 4, the group circuit breaker I is first opened to disconnect the supply circuit 2 from the load bus 3, then the circuit breaker 5 in the faulty'load circuit is opened and then the group feeder circuit breaker I is reclosed to reconnect the supply circuit 2 to the load bus 3 and the load circuits 4 which are still connected thereto.

With the arrangement shown in the drawing, it is necessary to arrange the operating values of trip coil 6 of the circuit breaker I and that of relay I3 associated with circuit breakers so that the amount of current in the load circuit 4 necessary to efiectthe operation of the overload relay I3 associated therewith is materially less than the amount of current in the supply circuit 2 necessary to effect the opening of the circuit breaker I. With such an arrangement there is a possibility that certain abnormal condition on a load circuit may effect the operation of the associated overload relay I3 without causing suflicient current to flow through the supply circuit 2 to effect the opening of the circuit breaker I. In accordance with one object of my invention, I provide an arrangement whereby under such conditions the operated overload relay I3 in the load circuit and its auxiliary relay I1 are restored to their normal positions if the circuit breaker I is not opened within a predetermined time after the overload relay I3 closes its contacts I5. In the particular embodiment of my invention shown in the drawing, this result is accomplished by means of two relays and 2|. The relay 20 is arranged so that it is energized when the contacts I5 of the overload relay I3 are closed and the associated circuit breaker 5 is closed. The relay 2D is arranged to close its contacts 22 after the winding of the relay has been energized a predetermined time. The closing of the contacts 22 completes an energizing circuit for the relay 2| which controls contacts 23 in the circuit of the holding winding I6 of the associated overload relay I3. The relay 2| is designed so that it opens its contacts 23 immediately after the winding of the relay is energized but preferably maintains these contacts open for a short 'time after the relay winding is deenergized. By

opening its contacts 23, the relay 2| effects the opening of the contacts I5 of the associated overload relay I3 and the deenergization of the associated auxiliary relay II.

In order to limit the number of times the circuit breaker I may be reclosed, I also provide suitable means, examples of which are well known in the art, for opening the energizing circuit of the closing coil 8 in case it is energized ,a predetermined number of times within a predetermined time interval. As shown in the drawing, this result is accomplished by means of a well known type of notching relay which has an operating coil connected in parallel with the closing coil 8 and which is arranged to open its manually closed contacts 21 inthe circuit of the closing coil 8 in case the operating coil 25 is energized a predetermined number of times vwith less than a predetermined time interval be- .tween each deenergization of the operating circuit breaker I, with the added result that suflicient current flows through the faulty load circuit to effect the closing of the contacts I5 of the overload relay I3 associated therewith. The closing of the contacts I5 completes through the auxiliary contacts 29 of the associated circuit breaker 5 and the contacts 23 of the relay 2| 23 of the circuit breaker.

energizing circuits for the holding coil I5 of the overload relay I3, the operating winding of the auxiliary relay l1 and the operating winding of the relay 2Il. Auxiliary relay II closes its contacts I8 so that as soon as the circuit breaker I opens, a circuit is completed for the trip coil III of the circuit breaker 5 in the faulty load circuit. This circuit includes the auxiliary contacts 30 of the open circuit breaker I, .the contacts I8 of the relay II, trip coil Ill and the contacts 3| of the closed circuit breaker 5. When the circuit breaker 5 in the faulty load circuit opens, the circuits of the holding coil I8 and the relays l1 and 2|! associated therewith are interrupted by the opening of the auxiliary contacts Before the relay II opens its contacts I8, however, circuits are completed through these contacts for the closing coil 8 of the circuit breaker I and the operating winding 25 or the notching relay 25. These circuits also include the auxiliary contacts 30 of the open circuit breaker I, contacts I8 of therelay I I, the auxiliary contacts 32of the open circuit breaker 5 and the contacts 21 of the notching relay 25. When the circuit breaker I closes, the circuits of the closing coil 8 and the operatinlg winding 26 of the notching relay 25 are interrupted by the opening of the auxiliary contacts 30 on the circuit breaker I.

If a plurality of faults occur within a predetermined time or some other abnormal condition occurs so that the operating winding 26 of the notching relay 25 is energized a'predetermined number of times with less than a predetermined time interval between each deenergization and the subsequent energization thereof, the notching relay opens its contacts 21 in the circuits of the closing coil 8 of the circuit breaker I and the operating winding 26 of the relay 25. Since the closing of contacts 21 is preferably manually controlled, it will be seen that the circuit breaker I cannot be reclosed again until the contacts 21 have been reset manually.

Let it be assumed now that a fault occurs on one of the load circuits 4 which causes the overload relay |3 associated therewith to close its contacts I5 but does not cause the trip coil 5 in the supply circuit to efiect the opening of the circuit breaker I. The closing of the contacts I5 of the overload relay I3 effects, in the manner above described, the energization of the associated auxiliary relay I1 and time relay 20. If the circuit breaker I does not open within a predetermined time after the overload relay I3 closes its contacts I5, the time relay 2D closes its contacts 22 and completes an energizing circuit for the relay 2;! which is arranged to open its contacts 23 immediately after its winding is energized. The opening of the contacts 23 interrupts the circuits of the holding winding I6 and the relays I1 and 20 so that these devices are restored to their normal positions without efiecting the opening of the associated circuit breaker 5. The return of relay 20 to its normal position causes the relay 2| to reclose its contacts 23 so that the control apparatus is again in condition to effect the opening of the circuit breaker I and the associated circuit breaker .5 upon the occurrence of another fault on the load circuit.

While I have, in accordance with the. patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I, therefore, aiinin the appended claims to cover all suchchanges and modifications asfall within the truev spirit and-scope of my invention.

What I claim as new and desire to secure by Letters Patent ofthe United States, is:

1'. In combination, a bus, a supply circuit, a

circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, aload circuit, a second" circuit breaker connecting" said load circuit to said bus, and means controlled by said; first mentioned circuit breaker and a-predetermined abnormal condition of said load circuit for eii'ecting the opening ofsaid second circuitbreaker' in response to saidpredetermined abnormal condition of said load circuit only if said first mentioned circuit breaker is open within a predetermined time after the occurrence of said abnormal condition.

2. In combination, a bus, a supply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, a load circuit, a second circuit breaker connecting said load circuit to said bus, means controlled by said first mentioned circuit breaker and a predetermined abnormal condition of said load circuit for efiecting the opening of said second circuit breaker in response to said predetermined abnormal condition of said load circuit only if said first mentioned circuit breaker is open within a predetermined time after the occurrence of said abnormal condition, and means responsive to the opening of said second circuit breaker for effecting the reclosing of said first mentioned circuit breaker.

3. In combination, a bus, a supply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, a load circuit, a second circuit breaker connecting said load circuit to said bus, means controlled by said first mentioned circuit breaker and a predetermined abnormal condition of said load circuit for efi'ecting the opening of said second circuit breaker in response to said predetermined abnormal condition of said load circuit only if said first mentioned circuit breaker is open within a predetermined time after the occurrence of said abnormal condition, means responsive to the opening of said second circuit breaker for eifecting the reclosing of said first mentioned circuit breaker, and means for limiting the number oi. reclosures of said second mentioned circuit breaker.

4. In combination, a bus, asupply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, a load circuit, a second circuit breaker connecting said load circuit to said bus, an overload relay responsive to the current in said load circuit, contacts controlled by said relay so that they are closed when the current in said load circuit exceeds a predetermined value, means independent of the current in said load circuit for maintaining said contacts in their closed position and means controlled by said contacts and said first mentioned circuit breaker for effecting the opening of said second circuit breaker when said contacts are closed and said first mentioned circuit breaker is open.

5. In combination, a bus, a supply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, a load circuit, a second circuit breaker connecting said load circuit to said bus, an overload relay responsive to the current in said load circuit, contacts. controlled by sai'd relay so that they are closed whenzt'he currentin said load circuit exceeds a-p'redetermined value, means for maintaining said contacts. in. their closed position, means controlled by'said contacts and said -r'st mentioned:circuitbreaker for efiecting the openingof said second circuit breaker when said contacts are closed and said first mentioned circuit breaker is open, and timing means controlled bysaid contacts for efiecting the opening of said contacts if said first mentioned circuit breaker isnot opened within a. predetermined time-after the-clos1ng of said contacts.

6. In combination, abus, a supply circuit, a

circuit breaker connecting said supply circuit to ing said load circuit to said bus, an overload relay responsive to the current in said load circuit, contacts controlled by said relay so that they are closed when the current in said load circuit exceeds a predetermined value, means independent of the current in said load circuit for maintaining said contacts in their closed position, and means controlled by said contacts and said first mentioned circuit breaker for efiecting the opening of said second circuit breaker when said contacts are closed and said first mentioned circuit breaker is open and for efiecting the reclosure of said first mentioned circuit breaker after said second circuit breaker opens.

7. In combination, a supply circuit, a circuit breaker in said supply circuit, means for opening said circuit breaker, a load circuit, a second circuit breaker in said load circuit, an overload relay responsive to the current in said load circuit, an auxiliary relay controlled by said overload relay so that it is energized when the current in said load circuit exceeds a predetermined value, contacts controlled by said auxiliary relay so that they are closed when said auxiliary relay is energized, means for delaying the opening of said contacts when said auxiliary relay is deenergized, means controlled by said second circuit breaker for effecting the deenergization of said auxiliary relay when said second circuit breaker opens, a trip circuit for said second circuit breaker controlled by said first mentioned circuit breaker and said contacts so that said second circuit breaker is opened when said first circuit breaker is open and said contacts are closed, and a closing circuit for said first mentioned circuit breaker controlled by said contacts and said second circuit breaker so that said first mentioned circuit breaker is closed when said second circuit breaker is open and said contacts are closed.

8. In combination, a bus, a supply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker, a load circuit, a second circuit breaker connecting said load circuit to said bus, a relay responsive to a predetermined abnormal condition of said load circuit, contacts controlled by said relay so that they are closed when said predetermined abnormal condition occurs, means independent of said abnormal condition for maintaining said contacts in their closed position and means controlled by said contacts and said first mentioned circuit breaker for effecting the opening of said second circuit breaker when said contacts are closed and said first mentioned circuit breaker is open.

9. In combination, a bus, a supply circuit, a circuit breaker connecting said supply circuit to said bus, means for opening said circuit breaker,

a load circuit, a second circuitbreaker connecting said load circuit to said bus, a relay responsive to a predetermined abnormal condition of said load circuit, contacts controlled by said relay so that they are closed when said predetermined abnormal condition occurs, means independent of said abnormal condition for maintaining said contacts in their closed position and means controlled by said contacts and said first mentioned ply circuit from said bus, fault responsive means foropening said eircuitbreaker to isolate said supply circuit from said bus, a load circuit, a sec-- and circuit breaker connecting said load circuit to said bus, a relay responsive to a predetermined abnormal value of current in said load circuit, contacts controlled by said relay so that they are closed in response to the operation of said relay, means [or maintaining said contacts in their closed position after said relay is deenergized by the opening of said first mentioned circuit-breaker, and means controlledby said contacts and said first mentioned circuit breaker for effecting the opening of said second-circuit breaker when said contacts are closed and said first mentioned circuit breaker is open.

I ARVID E. ANDERSON. 

